Tumor necrosis factor (TNF) receptor superfamily members regulate cellular proliferation, differentiation and apoptosis in inflammatory and immune responses. This receptor superfamily comprises a group of related cell-surface receptors including, but not limited to, types 1 and 2 TNF receptors (TNFR1 and TNFR2), Fas, CD27, 4-1BB, and CD30. Signaling through TNF receptor superfamily members is initiated by oligomerization of the receptors with trimeric ligands, bringing intracellular domains in close proximity (Baker and Reddy, Oncogene, 1998, 17, 3261-3270). These receptors are devoid of any intrinsic catalytic activity and therefore must recruit a variety of adaptor proteins to the cytoplasmic domain in order to relay the signals that eventually reach the nucleus. Two families of adaptor proteins that associate with TNF receptor superfamily members have been identified: the TNF receptor-associated factor (TRAF) family, and the death domain-containing protein family.
The mammalian TRAF family currently includes six members and these proteins have generally been found within the cytosols of cells, either in association with cytosolic vesicles or at the plasma membrane after addition of selected TNF family cytokines to the cells. TRAF family members have been shown to interact with and mediate signal from various subsets of TNF receptors. One such receptor, recently identified in dendritic cells and shown to enhance T-cell growth and dendritic cell function, is RANK (Receptor Activator of Nuclear Factor-kappa B) (Anderson et al., Nature, 1997, 390, 175-179; Green and Flavell, J. Exp. Med., 1999, 189, 1017-1020).
The nucleic acid and polypeptide sequences of human RANK are disclosed in the PCT publication WO 98/28424 as are antibodies to the RANK polypeptide, expression systems comprising vectors and host cells transformed with vectors encoding RANK and methods to regulate an immune or inflammatory response by treating an individual with soluble RANK polypeptide compositions. Sense and antisense oligonucleotides that hybridize to RANK DNA or mRNA are also generally disclosed (Anderson et al., 1998).
Signaling through RANK has been shown to activate both the NF-kappa-B pathway as well as the Jun N-terminal Kinase (JNK) pathway, and both occur via interactions with TRAF family proteins (Darnay et al., J. Biol. Chem., 1998, 273, 20551-20555).
NF-kappa-B proteins are involved in a diverse set of signaling pathways involving the immune response, apoptosis, cancer and growth. RANK has been shown to activate the NF-kappa-B pathway through its interaction with TRAF-2, 5 and 6 and another kinase, NF-kappa-B inducing kinase (NIK) (Darnay et al., J. Biol. Chem., 1999, 274, 7724-7731; Galibert et al., J. Biol. Chem., 1998, 273, 34120-34127; Wong et al., J. Biol. Chem., 1998, 273, 28355-28359).
Alternatively, interactions between RANK and TRAF-1, 2, 3, and 6 were shown to activate the JNK pathway (Kim et al., FEBS Lett., 1999, 443, 297-302). This pathway was originally identified as an oncogene- and ultraviolet light-stimulated kinase pathway but is now known to be activated by growth factors, cytokines and T-cell costimulation. The involvement of RANK with the JNK pathway has major implications for the role of RANK in multiple pathologic conditions, especially those initiated by cellular stressors such as cancer, and inflammatory responses.
More recently it has been demonstrated that RANK is essential to signaling pathways involved in bone morphogenesis, more specifically, osteoclastogenesis or the process of osteoclast differentiation (Nakagawa et al., Biochem. Biophys. Res. Commun., 1998, 253, 395-400). In these and other studies RANK was shown to be the receptor for osteoclast differentiation factor (ODF) and to mediate osteoclast differentiation, activation and, in some cases, osteoclast function (Hsu et al., Proc. Natl. Acad. Sci. U. S. A., 1999, 96, 3540-3545; Jimi et al., J. Immunol., 1999, 163, 434-442; Nakagawa et al., Biochem. Biophys. Res. Commun., 1998, 253, 395-400). These studies suggest that proper signaling through RANK is critical to the regulated homeostasis that must be maintained between the processes of bone formation by osteoblasts and bone resorption by osteoclasts.
Currently, there are no known therapeutic agents which effectively inhibit the synthesis of RANK and, therefore, the pharmacological modulation of RANK expression and/or function may be an appropriate point of therapeutic intervention in pathological conditions.
To date, investigative strategies aimed at modulating RANK function have involved the use of antibodies and strategies that block ligand-receptor interactions, such as the use of soluble receptors. However, these strategies are untested as therapeutic protocols and consequently, there remains a long felt need for additional agents capable of effectively inhibiting RANK function.
Antisense technology is emerging as an effective means for reducing the expression of specific gene products and may therefore prove to be uniquely useful in a number of therapeutic, diagnostic, and research applications for the modulation of RANK expression. The present invention provides compositions and methods for modulating RANK expression.